• A hydrologic map of the subglacial drainage system for each catchment should be constructed;

  • Potential target environments should be identified based on the subglacial drainage system.

Once potential research sites are identified, the likelihood of attaining scientific goals should be evaluated based on the representativeness for other lakes and settings, for accessibility, and for the constraints of logistics and cost. The committee recognizes that plans are underway to sample Lake Vostok, and in the longer term Lake Ellsworth and Lake Concordia. The data collected from these endeavors should be used to assess whether the levels of cleanliness suggested in Recommendation 7 are appropriate.

RESEARCH NEEDS

At present, no clean drilling, sampling or monitoring technologies have been developed for exploration of subglacial aquatic environments. Development of new technologies needs to focus on methods to reduce contamination and to assess the contaminant load after sterilization. A standard method to ensure cleanliness that can be verified in the field is a critical need.

To achieve these goals, research is needed in two main areas: (1) microbial background levels and instrument cleanliness, and (2) clean drilling fluids. The baseline levels of microbes in the glacial ice and subglacial waters and the basic chemistry of all phases of these environments are not well established. In the case of background microbial levels, it may be possible to obtain ice samples from the ICECUBE project to investigate microbial background loadings in the glacial ice and the base-level contamination of hot-water drilling. Research from accretion ice cores is also needed to establish partition coefficients, which will help establish contamination limits. Using various technologies, it is necessary to assess the impacts of access and sampling and provide data to develop improved technologies for easier and cleaner access in the future.

Although hot-water drilling presents the greatest possibility for clean drill fluids, the time that a hole can be kept open and the depth to which hot-water holes can be drilled are limited. Drill fluids that do not freeze (e.g., jet fuel) have significant levels of biological contamination, but these fluids can provide indefinite access to a lake with periodic maintenance of the hole. New types of drilling fluids are needed that would not be substrates for microbial growth. Methods to clean the fluids prior to field deployment, as well as methods to clean them in the field, are also required. Development of filtering methods for borehole and drilling fluids may prove effective, along with in-line ultraviolet (UV) sterilization techniques or the addition of bactericides to the drilling fluids. It will be important to assess and document the biological and chemical contaminant content of all fluids used.

Cleaner monitoring and sampling technologies will have to be developed. Some priority areas include the following examples. Inert tracers in the drill fluid or fluid used to enter the lake need to be developed to track the level and distribution of contaminants within the lake. Development of miniaturized monitoring equipment will make it easier both to insert observatories into the water bodies and to retrieve them. A remote observatory designed for subglacial aquatic environments that could be inserted through a small borehole could provide long-term monitoring of the water or



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